iOS 3: set to off by default. To enable would require turning on DiagnosticsAllowed in “com.apple.iqagent preferences — which it does not appear to be enabled on any of my devices”

iOS 4: “Unknown, probably like iOS 3″

iOS 5: “Set by the ‘Submit Logs to Apple’ option during the iOS 5 setup sequence, and so Carrier IQ logging is toggled with that setting.”

Major differences with Android version:

1. Is this version of Carrier IQ the same keylogger/rootkit as on Android?

I am reasonably sure it has no access to typed text, web history, passwords, browsing history, or text messages, and as such is not sending any of this data remotely.

2. It is op-in with iOS 5.

iOS 5 asks users if they want to turn on sending diagnostics data to Apple. The default is OFF.

3. You can turn it off Carrier IQ in iOS.

If you want to disable Carrier IQ on your iOS 5 device, turning off “Diagnostics and Usage” in Settings appears to be enough.

In contrast, Android version can keep track of everything including encrypted web traffic (such as bank account / password), text messages, etc. In addition, Android version cannot be turned off easily. Again, Carrier IQ is OFF BY DEFAULT on iOS. But on Android it is installed and activated on select devices by manufacturer upon carrier request.